When I try to login with some other id that root I get a messge dl_boot:
can not open /dev/zero and it's going back to the login prompt. su does
not want to switch to another name also. /dev/zero is on its place, it
has crw-rw-rw permissions, the permissions on my /dev directory are o.k.
and I do not have any nologin file in all my filesystems and no backups
to restore from. What's the trick?